Controlling system for positioning a swashplate of a multiple-piston rotary fluid pump or motor

ABSTRACT

A controlling system for positioning a swashplate of a multiplepiston rotary fluid pump or motor, comprising a servo piston, a changeover valve, an operating lever, and a link mechanism connecting the above three components one after another. When the operating lever is swung, the changeover valve is slid intermediate the link mechanism so as to actuate the servo piston and vary the inclination of the swashplate. By the sliding of the servo piston, the changeover valve is again slid to the neutral position. When the inclination of the swashplate is forced to be varied from the multiple pistons, the changeover valve serves to resist such variation.

United States Patent CONTROLLING SYSTEM FOR POSITIONING A SWASI-IPLATEOF A MULTIPLE-PISTON ROTARY FLUID PUMP 0R MOTOR 7 Claims, 3 DrawingFigs.

US. Cl 91/505, 60/52 VS, 91/384 Int. Cl. F0lb 3/00, FOlb 13/04, F15b9/10 Field of Search 91/505,

Primary ExaminerCarlton R. Croyle Assistant Examiner.lohn .l. VrablikAttorney-Steinberg & Blake ABSTRACT: A controlling system forpositioning a swashplate of a multiple-piston rotary fluid pump ormotor, comprising a servo piston, a changeover valve, an operatinglever, and a link mechanism connecting the above three components oneafter another. When the operating lever is swung, the changeover valveis slid intermediate the link mechanism so as to actuate the servopiston and vary the inclination of the swashplate. By the sliding of theservo piston, the changeover valve is again slid to the neutralposition. When the inclination of the swashplate is forced to be variedfrom the multiple pistons, the changeover valve serves to resist suchvariation.

CONTROLLING SYSTEM FOR POSITIONING A SWASIIPLATE OF A MULTIPLE-PISTONROTARY FLUID PUMP R MOTOR This invention relates to improvements in acontrolling system for positioning a swashplate of a multiple-pistonrotary fluid pump or motor, that is, a variable displacement plungerpump, whereby a displacement thereof is varied.

l-Ieretofore, in case an engine comprising such a pump or motor of theclass described of a hydraulically driven car or the like accidentallystops, there is a disadvantage such that a controlling pressure forcontrolling a servo piston which controls the inclination of aswashplate is not obtained and therefore the swashplate is not restoredto its neutral position, ending in that it is impossible to push or pullthe car by another car.

The primary object of this invention is to provide a controlling systemand a means therefor improved for overcoming the above defect.

Another object of this invention is to provide a controlling system ofthe class described, in which slight inclination of the swashplate to bederived from variation in load externally subjected to the pump andunbalanced moments by itself are not directly transmitted to other partsas excessive loads.

Still another object of this invention is to provide a controllingsystem of the class described, in which the servo piston is movable wellin response to the theoretical output of the charging circuit.

Briefly stated in accordance with one aspect of this invention, there isprovided a controlling system for positioning a swashplate of amultiple-piston rotary fluid pump or motor, comprising a changeovervalve adapted to be slid by an operating lever intermediate a linkmechanism for actuating a servo piston by acting a pressured fluidmedium thereto whereby the inclination of the swashplate is varied andthe changeover valve is restored. By virtue of the actuation of theservo piston intermediate the link mechanism, the action of thepressured fluid medium is interrupted.

In accordance with this invention, a multiple-piston rotary fluid pumpor motor having a swashplate, comprises, in combination, a servo piston,of which a piston rod is connected with a displaceable link at a pivoton an. end of the displaceable link, and adapted to control theinclination of the swashplate, a changeover valve having a spool, ofwhich the valve rod is connected with the displaceable link at anintermediate point thereof, and adapted to control the servo piston, andan operating lever connected with the displaceable link at another pivoton the other end of the displaceable link for operating the changeovervalve, the spool being adapted to be slid in the changeover valve alongsuch a stroke when the firstnamed pivot is a fulcrum, as equal withanother stroke along which the spool is adapted to be slid when theanother pivot is another fulcrum.

By virtue of this controlling system, any variation in the operatingspeed of the operating lever does not relate to the sliding speed of theservo piston and other balancing relations in pressure. It is possibleto operate the operating lever at an optional speed without anyunreasonableness in the link mechanism.

By virtue of this controlling system, when the inclination of theswashplate is slightly varied by the action of the multiple pistons ofthe pump or motor, the pressured fluid medium is admitted to act oneither side of the servo piston so as to resist the sliding motion ofthe latter and interrupt the transmission of the variation in load, andtherefore, a margin in strength of the construction may be left. Thusany external variation in load subjected to the swashplate and-anyinternal unbalancing moment, which acts on the swashplate so as toslightly vary the inclination thereof, are not directly transmitted tolink mechanism. By virtue of this fact, it is possible to provide aneutral returning spring for the swashplate in such a manner that therotation thereof is not disturbed, and therefore, it is very easy torestore the swashplate to the neutral position.

By virtue of this controlling system, the changeover valve is operatedat a speed in proportion to the operating speed of the controlling leverand yet the servo piston is not forcedly slid in accordance with theoperation of the operating lever, and therefore, the servo piston ismoved in response to a theoretical output of a charging circuit thereforwithout any influence of a sliding friction and an unbalance due to aback pressure.

The invention will be better understood and other objects and additionaladvantages of the invention will become apparent upon perusal of thefollowing description taken in connection with the drawings, in which:

FIG. I is a schematic view of a controlling means embodying thisinvention, in which a swashplate is in its neutral position;

FIG. 2 is an enlarged cross-sectional view of a friction clutch providedin the controlling means; and

FIG. 3 is a schematic view similar to FIG. 1 but showing the swashplatein its inclined position.

Similar numerals refer to similar parts throughout the three views. I

Referring more particularly to the drawings, the preferred embodiment ofthis invention will now be described; however, the description will beunderstood to be illustrative of the invention and not as limiting it tothe particular construction shown and described. A variable displacementplunger pump 1 l is provided with a swashplate l2 and with a neutralposition restoring means 18. That is, the neutral position restoringmeans 18 is connected with an end 12a of the swashplate by a connectinglink 30 for restoring the swashplate 12 into the neutral position. Thevariable displacement plunger pump 11 is adapted to be driven by anengine and drive a fluid medium when the swashplate I2 is inclined. Theinclination of the swashplate I2 is controlled by means of a servopiston 13 as shown in FIGS. 1 and 3. The extent of the inclination ofthe swashplate is about 2. The servo piston I3 is hydraulically drivenby a fluid medium supplied from a fixed displacement pump 50 through afluid duct 51. The fixed displacement pump 50 is connected with areservoir 53 through a filter 52. The fluid duct 51 is branched to thereservoir 53 through a check valve 21.

A pin 13 rotatably mounted on the servo piston 13 is adapted to beslidably inserted in a slot 12b formed in the other end of theswashplate 12. A changeover valve 14 having a spool is connected to thefluid duct 51 so as to change over the fluid duct 51 to direct thepressured fluid medium to either side of the servo piston 13.

There is a displaceable link 32, of which a pivot A on an end thereof ispivoted with a piston rod I3a by a link 31. Another pivot C formed at anintermediate part of the displaceable link 32 is connected with an endof a valve rod of the spool of the changeover valve 14 intermediate alink 33. The spool comprises three parts: a pair of parallel flowpassages arranged in the left part thereof, a pair of neutral flowpassages in the central part thereof, and a pair of crossflow passagesin the right part thereof, as shown in FIGS. 1 and 3. The other end ofthe valve rod of the spool of the changeover valve 14 is connected witha returning spring means 15, which serves for positioning the spool andfacilitates the returning motion thereof.

The other end of the displaceable link 32 is provided with still anotherpivot B, on which the displaceable link 32 is connected with anoperating lever 17 by a connecting link 34, a connecting lever 16 and afriction clutch comprisinga lining I9 and an initially coned disc spring20 mounted on a rotary shaft 22, on which the connecting lever 16 andthe operating lever 17 are fixed, as shown in FIG. 2.

In operation, when the swashplate I2 is not inclined for any reason,when the operating lever 17 is swung in the counterclockwise directionin FIG. I from the neutral position, the displaceable link 32 is swungin the clockwise direction in FIG. I on the fulcrum A, because theswashplate I2 is not inclined, so that the servo piston 13 is not slidand the pivot A is not displaced. When the displaceable link 32 is swungin the clockwise direction as above, the link 33 is displaced leftwardtogether with the valve rod of the spool of the changeover valve 14, sothat the pressured fluid duct 51 is changed over from the centralneutral flow passages to the right crossflow passages of the spool. Whenthe pressured fluid duct 51 is changed over as above, the fluid mediumpressured by the fixed displacement pump 50 is admitted into a space onthe left side of the servo piston 13 through the crossflow passages soas to slide the servo piston 13 rightward, to incline the swashplate 12as shown in FIG. 3. Upon inclination of the swashplate 12, the variabledisplacement plunger pump 11 may serve for translating power to eitherdirection.

The pivot B is displaced to another position B whereby the pivot A isindirectly displaced to another position A. In this case the rightwarddisplacement of the servo piston 13 together with the pivot A causes arightward displacement of the intermediate pivot C together with thevalve rod and the spool of the changeover valve 14, because the pivot 13in the position B is fixed thereto together with the connecting link 34by virtue of the friction clutch and serves as a fulcrum on which thedisplaceable link 32 is swung in the clockwise direction in FIG. 1. Whenthe spool is thus slid rightward into the neutral position, thecommunication of the pressured fluid medium through the crossflowpassages of the spool is interrupted as shown in FIG. 3.

When the operating lever 17 is swung in the clockwise direction in FIG.1, it will be apparent that the swashplate 12 is inclined in theopposite direction to the above-mentioned motion, and yet the changeovervalve 14 is restored to its neutral position. That is, the spool of thechangeover valve 14 is at first slid rightward, ending in that thepressured fluid medium is fed into a space on the right side of theservo piston 13 through the parallel flow passages of the spool.Secondary the leftward displacement of the servo piston 13 accompanyingthe counterclockwise swinging of the displaceable link 32 causes therestoration of the spool into the neutral position thereof.

When the inclination of the swashplate 12 is slightly varied by theaction of the variable displacement plunger pump 11,

such a variation is not transmitted to the operating system in thefollowing manner. For example, when a component of a force intends torestore the swashplate l2 inclined as shown in FIG. 3 to the neutralposition, the servo piston 13 is rendered to be slid leftward. Becausethe pivot B in the position B is fixed by virtue of the friction clutch,the displaceable link 32 is swung in the counterclockwise direction inFIG. 3 on the fulcrum B and the spool of the changeover valve 14 is slidleftward. When the spool is displaced from its neutral position to thecrossflow passages, the pressured fluid medium is admitted into thespace of the left side of the servo piston 13 so as to push it rightwardand the inclination of the swashplate 12 is restored. Thus by virtue ofthe controlling system in accordance with this invention, anyfluctuation in position of the swashplate 12 is resisted automaticallyhydraulically.

It is thus apparent from the above description that the swashplate 12 isoperatively connected directly to a single servo piston means 13 so thatthe position of the single piston 13 will always correspond to a givenangular position of the swashplate 12, as is apparent from a comparisonof FIGS. 1 and 3, for example. The single elongated control link means32 is pivotally connected at one end to the single servo piston meansand at its opposite end to a manually operable means formed by thelevers 16 and 17 with the rod 22 interconnecting the latter. Thefriction clutch assembly 19, 20 forms a retaining means for releasablyretaining the manually operable means l6, 17, 22 in the position towhich it is manually displaced. Between its ends which are thusrespectively pivotally connected directly to the single servo pistonmeans 13 and the manually operable means, the single elongated linkmeans 32 is pivotally connected to the single spool valve means 14 whichhas the central neutral portion providing communication between the endsof the cylinder of the single servo piston means and the pair of endportions between which the central neutral portion is located, with oneof these end portions providing for a flow of fluid to induce movementof the servo piston means in one direction and with the other of the endportions providing for a flow of fluid which will bring about movementof the servo piston means in the opposite direction. These end portionsof the spool valve means will always provide for the single servo pistonmeans a direction of movement which will act through the single linkmeans 32 with its connection to the manually operable means as a fulcrumto restore the spool valve means to its neutral position so that in thisway any tendency of the swashplate to be moved away from its adjustedposition will be opposed with automatic return of the swashplate to itsadjusted position, and with this construction the forces which tend todisplace the swashplate from its adjusted position will not betransmitted to the linkage components. On the other hand, when themanually operable means is moved by the operator the single elongatedlink means 32 will swing about its connection to the single servo pistonmeans as a fulcrum, for displacing the single spool valve means in onedirection or the other bringing about a corresponding change in theadjusted angle of the swashplate, and with the manually operable meansretained in its set position by the retaining means formed by thefriction clutch, the movement of the single servo piston means willagain operate to restore the single spool valve means to its neutralposition, thus providing a predetermined inclination for the swashplate.The means 18 forms a spring means urging the swashplate back toward itsneutral position, and it will be noted that this single spring means 18is connected only to one part of the swashplate, at a portion of thelatter opposed to the part of the swashplate which is connected to thesingle servo piston means. Also the spring means 15 forms a means whichacts on the spool valve means to continuously urge the latter to returnto its neutral position, so that the operation is enhanced by the springmeans 15.

While a preferred embodiment of the invention has been shown anddescribed, modifications thereof will readily occur to those skilled inthe art. It should be understood therefore that the invention is notlimited to the particular arrangement disclosed but that the appendedclaims are intended to cover all modifications which do not depart fromthe true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. In a multiple-piston rotary fluid pump or motor, a tiltableswashplate tiltable about a predetermined axis, a single servo pistonmeans operatively connected with said swashplate for tilting the latterabout said axis, said single servo piston means including a single servopiston and a cylinder in which the latter is movable, so that theangular position of the swashplate will always correspond to a givenposition of the single servo piston in its cylinder, a single spoolvalve means having'a central neutral portion for providing communicationbetween opposed ends of the cylinder of said single servo piston meansand a pair of end portions one of which provides for movement of saidsingle servo piston in one direction in said cylinder and the other ofwhich provides for movement of said single servo piston in the oppositedirection in said cylinder, manually operable means for manually settingthe angular position of the swashplate, a single elongated link meanshaving opposed ends respectively connected pivotally to said singleservo piston and said manually operable means, said single elongatedlink means being pivotally connected intermediate its ends to saidsingle spool valve means, so that said manually operable means may beoperated to swing said single link means about its connection to saidsingle servo piston means for displacing said single spool valve meansin a direction which will bring about movement of said servo piston toadjust the angle of the swashplate while restoring said spool valvemeans to its neutral position where said central portion thereofprovides communication between the opposed ends of said cylinder, andretaining means coacting with said manually operable means forreleasably retaining the latter in the position to which it is moved bythe operator, so that when a force tends to displace said swashplatefrom its adjusted angle the single servo piston will move to tilt thesingle link means about its connection to said manually operable meansfor displacing said spool valve means in a direction which willautomatically return the single servo piston to its adjusted positionand thus return the swashplate to its adjusted position.

2. The combination of claim 1 and wherein a spring means is operativelyconnected to said single spool valve means for urging the latter back toits neutral position.

3. The combination of claim 1 and wherein said retaining means is afriction clutch.

4. The combination of claim 1 and wherein three links are respectivelypivotally connected directly to said single servo piston, said singlespool valve means, and said manually operable means, and are allconnected directly to said single elongated link means for providing thepivotal connection between the latter and said single servo pistonmeans, said spool valve means, and said manually operable means 5. Thecombination of claim 1 and wherein said manually operable means includesa pair of levers and a single rod ex tending between and fixed to saidlevers, said rod being supported for rotary movement so that saidmanually operable means is turnable about the axis of said rod, one ofsaid levers being connected with said link means and the other of saidlevers being available for manual movement.

6. The combination of claim I and wherein a spring means is operativelyconnected to said swashplate for urging the latter to a neutralposition.

7. The combination of claim 6 and wherein said spring means isoperatively connected to said swashplate at a part thereof opposed to apart of the swashplate which is directly connected to said single servopiston means.

1. In a multiple-piston rotary fluid pump or motor, a tiltableswashplate tiltable about a predetermined axis, a single servo pistonmeans operatively connected with said swashplate for tilting the latterabout said axis, said single servo piston means including a single servopiston and a cylinder in which the latter is movable, so that theangular position of the swashplate will always correspond to a givenposition of the single servo piston in its cylinder, a single spoolvalve means having a central neutral portion for providing communicationbetween opposed ends of the cylinder of said single servo piston meansand a pair of end portions one of which provides for movement of saidsingle servo piston in one direction in said cylinder and the other ofwhich provides for movement of said single servo piston in the oppositedirection in said cylinder, manually operable means for manually settingthe angular position of the swashplate, a single elongated link meanshaving opposed ends respectively connected pivotally to said singleservo piston and said manually operable means, said single elongatedlink means being pivotally connected intermediate its ends to saidsingle spool valve means, so that said manually operable means may beoperated to swing said single link means about its connection to saidsingle servo piston means for displacing said single spool valve meansin a direction which will bring about movement of said servo piston toadjust the angle of the swashplate while restoring said spool valvemeans to its neutral position where said central portion thereofprovides communication between the opposed ends of said cylinder, andretaining means coacting with said manually operable means forreleasably retaining the latter in the position to which it is moved bythe operator, so that when a force tends to displace said swashplatefrom its adjusted angle the single servo piston will move to tilt thesingle link means about its connection to said manually operable meansfor displacing said spool valve means in a direction which willautomatically return the single servo piston to its adjusted positionand thus return the swashplate to its adjusted position.
 2. Thecombination of claim 1 and wherein a spring means is operativelyconnected to said single spool valve means for urging the latter back toits neutral position.
 3. The combination of claim 1 and wherein saidretaining means is a friction clutch.
 4. The combination of claim 1 andwherein three links are respectively pivotally connected directly tosaid single servo piston, said single spool valve means, and saidmanually operable means, and are all connected directly to said singleelongated link means for providing the pivotal connection between thelatter and said single servo piston means, said spool valve means, andsaid manually operable means.
 5. The combination of claim 1 and whereinsaid manually operable means includes a pair of levers and a single rodextending between and fixed to said levers, said rod being supported forrotary movement so that said manually operable means is turnable aboutthe axis of said rod, one of said levers being connected with said linkmeans and the other of said levers being available for manual movement.6. The combination of claim 1 and wherein a spring means is operativelyconnected to said swashplate for urging the latter to a neutralposition.
 7. The combination of claim 6 and wherein said spring means isoperatively connected to said swashplate at a part thereof opposed to apart of the swashplate which is directly connected to said single servopiston means.